U.S. patent application number 12/075184 was filed with the patent office on 2009-09-10 for led-based lighting system and method.
This patent application is currently assigned to Cooper Technologies Company. Invention is credited to Ellis W. Patrick.
Application Number | 20090225549 12/075184 |
Document ID | / |
Family ID | 41053407 |
Filed Date | 2009-09-10 |
United States Patent
Application |
20090225549 |
Kind Code |
A1 |
Patrick; Ellis W. |
September 10, 2009 |
LED-based lighting system and method
Abstract
A lighting system comprises a row of light emitting diodes
("LEDs") receiving electricity and producing light and heat. The
row of LEDs can be located in a channel or a groove of a piece of
material, such as an aluminum extrusion or a bent piece of metal.
The channel can have an optically reflective lining, for example,
providing either diffuse or specular reflection. Accordingly, the
channel can reflect light emitted by the LEDs. The piece of
material can also include a heat sink for transferring heat from
the LEDs to air via convection or air flow. The heat sink can
comprise fins or protrusions that facilitate convection.
Inventors: |
Patrick; Ellis W.;
(Sharpsburg, GA) |
Correspondence
Address: |
KING & SPALDING
1180 PEACHTREE STREET , NE
ATLANTA
GA
30309-3521
US
|
Assignee: |
Cooper Technologies Company
Houston
TX
|
Family ID: |
41053407 |
Appl. No.: |
12/075184 |
Filed: |
March 10, 2008 |
Current U.S.
Class: |
362/294 |
Current CPC
Class: |
F21V 29/505 20150115;
F21S 8/04 20130101; F21Y 2115/10 20160801; F21V 29/77 20150115 |
Class at
Publication: |
362/294 |
International
Class: |
F21V 29/00 20060101
F21V029/00 |
Claims
1. A lighting system, comprising: a member that comprises: a
channel having an optically reflective surface; and a plurality of
protrusions running alongside the channel; and a row of light
emitting diodes disposed in the channel.
2. The lighting system of claim 1, wherein the optically reflective
surface lines the channel and comprises a metallic surface, and
wherein the plurality of protrusions are disposed outside the
channel and are operative to dissipate heat produced by the row of
light emitting diodes.
3. The lighting system of claim 1, further comprising a heat
conductive path, consisting of one or more solid materials,
operative to conduct heat from the row of light emitting diodes to
the plurality of protrusions, and wherein the plurality of
protrusions are operative to dissipate the conducted heat via
convection.
4. The lighting system of claim 1, wherein each light emitting
diode in the row of light emitting diodes is mounted on a
respective substrate that is in thermal contact with the
member.
5. The lighting system of claim 1, wherein the channel extends
around a periphery of a luminaire, and wherein the row of light
emitting diodes extends around the periphery of the luminaire.
6. The lighting system of claim 1, wherein the channel extends to
form a rectangle, and wherein the plurality of protrusions running
alongside the channel are disposed behind the channel.
7. The lighting system of claim 1, further comprising: a second
channel adjacent the channel; and a second row of light emitting
diodes disposed in the second channel.
8. An lighting system, comprising: a light source disposed in a
cavity; and a member comprising: a concave, optically reflective
surface forming the cavity; and another surface, opposite the
concave, optically reflective surface, comprising a plurality of
protrusions operative to dissipate heat produced by the light
source.
9. The lighting system of claim 8, wherein the light source
comprises a light emitting diode mounted on a substrate that is in
contact with the member, wherein the another surface comprises a
heat sink, and wherein the plurality of protrusions comprises a
plurality of fins.
10. The lighting system of claim 8, wherein the member, the
plurality of protrusions, and the cavity extend lengthwise along a
common axis.
11. The lighting system of claim 10, wherein the light source
comprises a plurality of light emitting diodes respectively
attached to the member and disposed along the common axis.
12. The lighting system of claim 8, wherein the member and the
cavity extend around a periphery of a lighting fixture, and wherein
the light source comprises a plurality of light emitting diodes
respectively disposed at regular intervals around the
periphery.
13. The lighting system of claim 12, wherein the periphery forms a
square or a rectangle.
14. The lighting system of claim 8, wherein the member and the
cavity extend longitudinally, and wherein the illumination system
further comprises: a second member extending longitudinally
alongside the member and comprising: a second concave, optically
reflective surface forming a second cavity; and a second surface
opposite the second concave, optically reflective surface, the
second surface comprising a plurality of second protrusions
operative to dissipate heat; and a plurality of light emitting
diodes disposed generally in a line in the second cavity.
15. The lighting system of claim 8, wherein the optically
reflective surface comprises a metallic surface.
16. The lighting system of claim 8, wherein the light source
comprises a light emitting diode mounted to a thermally conductive
substrate that adjoins the member.
17. A luminaire, comprising: a first member comprising: a first
channel providing a first surface that is reflective to visible
light emitted from one or more first lighting elements disposed in
the first channel; a plurality of first fins, disposed outside the
first channel and extending generally parallel to the first
channel, that are operative to convect heat from the first member
to air; and a slot extending generally parallel to the first
channel; and a second member comprising: a second channel providing
a second surface that is reflective to visible light emitted from
one or more second lighting elements disposed in the second
channel; a plurality of second fins, disposed outside the second
channel and extending generally parallel to the second channel,
that are operative to convect heat from the second member to air;
and a protrusion extending generally parallel to the second
channel, wherein the protrusion is disposed in the slot.
18. The luminaire of claim 17, wherein the protrusion and the slot
are mated to one another.
19. The luminaire of claim 17, wherein the slot captures the
protrusion, and wherein the slot and the protrusion cooperate to
provide alignment between the first member and the second
member.
20. An optical system, comprising a body of material that
comprises: a finned surface operative to dissipate heat produced in
response to converting electricity into light; and a concave
surface operative to reflect the light.
21. The optical system of claim 20, wherein the body of material
comprises metal coated with an optically reflective material.
22. The optical system of claim 20, wherein the concave surface and
fins of the finned surface extend lengthwise essentially parallel
to one another.
23. The optical system of claim 20, wherein the concave surface
extends around a luminaire, and wherein the optical system further
comprises a light emitting diode that is operative to produce the
heat as a byproduct of converting the electricity into the
light.
24. An illumination system, comprising: a body of material that
comprises: a first surface contour that reflects light; and a
second surface contour that transfers heat to air via convection;
and a light emitting diode, mounted to the body of material and
disposed adjacent the first surface contour, operative to convert
electrical energy into the light and the heat.
25. The illumination system of claim 24, further comprising: an
optical coating on the first surface contour for enhancing light
reflection; and a thermal path, consisting of one or more solid
heat-conducting materials, extending from the light emitting diode
to the second surface contour.
Description
TECHNICAL FIELD
[0001] The present invention relates to illumination systems
utilizing light emitting diodes ("LEDs") to provide visible or
substantially white light, and more specifically to a luminaire
incorporating a row of LEDs located in a reflective channel with a
heat sink disposed alongside or behind the channel.
BACKGROUND
[0002] LEDs offer benefits over incandescent and fluorescent lights
as sources of illumination. Such benefits include high energy
efficiency and longevity. To produce a given output of light, an
LED consumes less electricity than an incandescent or a fluorescent
light. And, on average, the LED will last longer before
failing.
[0003] The level of light a typical LED outputs depends upon the
amount of electrical current supplied to the LED and upon the
operating temperature of the LED. That is, the intensity of light
emitted by an LED changes according to electrical current and LED
temperature. Operating temperature also impacts the usable lifetime
of most LEDs.
[0004] As a byproduct of converting electricity into light, LEDs
generate heat that can raise the operating temperature if allowed
to accumulate, resulting in efficiency degradation and premature
failure. The conventional technologies available for handling and
removing this heat are generally limited in terms of performance
and integration. For example, most heat management systems are
separated from the optical systems that handle the light output by
the LEDs. The lack of integration often fails to provide a
desirable level of compactness or to support efficient luminaire
manufacturing.
[0005] Accordingly, to address these representative deficiencies in
the art, an improved technology for managing the heat and light
LEDs produce is needed. A need also exists for an integrated system
that can manage heat and light in an LED-base luminaire. Yet
another need exists for technology to remove heat via convection
and conduction while controlling light with a suitable level of
finesse. Still another need exists for an integrated system that
provides thermal management, mechanical support, and optical
control. An additional need exists for a compact lighting system
having a design supporting low-cost manufacture. A capability
addressing one or more of the aforementioned needs (or some similar
lacking in the field) would advance LED lighting.
SUMMARY
[0006] The present invention can support illuminating an area or a
space to promote observing or viewing items located therein. A
lighting system comprising a light source, such as an LED, can
comprise one or more provisions for managing light and heat
generated by a light source. Managing heat can enhance efficiency
and extend the source's life. Managing light can provide a
beneficial illumination pattern.
[0007] In one aspect of the present invention, a lighting system,
apparatus, luminaire, or device can comprise a row of LEDs. The row
of LEDs, which are not necessarily in a perfect line with respect
to one another, can emit or produce visible light, for example
light that is white, red, blue, green, purple, violet, yellow,
multicolor, etc. Additionally, the light can have a wavelength or
frequency that a typical human can perceive visually. The emitted
light can comprise photons, luminous energy, electromagnetic waves,
radiation, or radiant energy.
[0008] The lighting system can further comprise one or more
capabilities, elements, features, or provisions for managing light
and heat produced by the row of LEDs. The row of LEDs can be
disposed in a channel having a reflective lining or reflective
sidewalls. That is, the LEDs can be located in a groove, an
elongate cavity, a trough, or a trench with a surface for
reflecting light the LEDs produce. The surface can be either
smoothly polished to support specular reflection or roughened to
support diffuse reflection. Accordingly, the channel can manage
light from the LEDs via reflection. One or more features for
managing heat produced by the LEDs can extend or run alongside the
channel. For example, one or more protrusions, fins, or flutes can
be located next to the channel. The features running alongside the
channel can be behind the channel, in front of the channel, beside
the channel, next to the channel, above the channel, adjacent the
channel, beneath the channel, etc. Managing heat produced by the
LEDs can comprise transferring the heat to air via air circulation
or air movement.
[0009] The discussion of managing heat and light produced by LEDs
presented in this summary is for illustrative purposes only.
Various aspects of the present invention may be more clearly
understood and appreciated from a review of the following detailed
description of the disclosed embodiments and by reference to the
drawings and the claims that follow. Moreover, other aspects,
systems, methods, features, advantages, and objects of the present
invention will become apparent to one having ordinary skill in the
art upon examination of the following drawings and detailed
description. It is intended that all such aspects, systems,
methods, features, advantages, and objects are included within this
description, are within the scope of the present invention, and are
protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view from below of a lighting system
comprising LEDs and a capability for managing heat and light output
by the LEDs in accordance with certain exemplary embodiments of the
present invention.
[0011] FIG. 2 is a perspective view from above of a lighting system
comprising LEDs and a capability for managing heat and light output
by the LEDs in accordance with certain exemplary embodiments of the
present invention.
[0012] FIG. 3 is a detail view of a portion of a lighting system,
illustrating two rows of LEDs respectively disposed in two
channels, each formed in a member, in accordance with certain
exemplary embodiments of the present invention.
[0013] FIG. 4 is a line drawing providing an internal view of a
portion of a lighting system, illustrating thermal management
features in accordance with certain exemplary embodiments of the
present invention.
[0014] FIG. 5 is a cross sectional view of two members of a
lighting system, each providing integrated light management and
thermal management in accordance with certain exemplary embodiments
of the present invention.
[0015] FIG. 6 is a plot of simulated thermal contours of a portion
of a lighting system providing integrated light management and
thermal management in accordance with certain exemplary embodiments
of the present invention.
[0016] FIG. 7 is a plot of simulated thermal contours of a lighting
system comprising LEDs and a capability for managing heat and light
output by the LEDs in accordance with certain exemplary embodiments
of the present invention.
[0017] FIG. 8 is a flowchart of a method of operation of a lighting
system comprising LEDs and a capability for managing heat and light
output by the LEDs in accordance with certain exemplary embodiments
of the present invention.
[0018] Many aspects of the invention can be better understood with
reference to the above drawings. The elements and features shown in
the drawings are not necessarily to scale, emphasis instead being
placed upon clearly illustrating the principles of exemplary
embodiments of the present invention. Additionally, certain
dimensions may be exaggerated to help visually convey such
principles. In the drawings, reference numerals designate like or
corresponding, but not necessarily identical, elements throughout
the several views.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0019] An exemplary embodiment of the present invention supports
reliably and efficiently operating an LED-based lighting system or
luminaire that is compact and configured for cost-effective
fabrication. The lighting system can comprise a structural element
that manages heat and light output by one or more LEDs. Fins,
protrusions, or grooves can provide thermal management via
promoting convection. A channel comprising a reflective lining can
provide light management via diffuse or specular reflection or a
combination of diffuse and specular reflection.
[0020] A lighting system will now be described more fully
hereinafter with reference to FIGS. 1-8, which describe
representative embodiments of the present invention. FIGS. 1-5
generally depict a representative LED-based lighting system with
provisions for thermal and light management. FIGS. 6 and 7
illustrate simulated thermal performance of an reprsentative
LED-based lighting system. Finally, FIG. 8 provides a method of
operation of an LED-based lighting system.
[0021] The invention can be embodied in many different forms and
should not be construed as limited to the embodiments set forth
herein; rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the invention to those having ordinary skill in the art.
Furthermore, all "examples" or "exemplary embodiments" given herein
are intended to be non-limiting, and among others supported by
representations of the present invention.
[0022] Turning now to FIGS. 1 and 2, these figures illustrate a
lighting system 100 comprising LEDs (specifically the rows of LEDs
125) and a capability for managing heat and light output by the
LEDs in accordance with certain exemplary embodiments of the
present invention. FIG. 1 provides a perspective view from below,
while FIG. 2 presents a top perspective.
[0023] In an exemplary embodiment, the lighting system 100 can be a
luminaire or a lighting fixture for illuminating a space or an area
that people may occupy or observe. In one exemplary embodiment, the
lighting system 100 can be a luminaire suited for mounting to a
ceiling of a parking garage or a similar structure.
[0024] The term "luminaire," as used herein, generally refers to a
system for producing, controlling, and/or distributing light for
illumination. A luminaire can be a system outputting or
distributing light into an environment so that people can observe
items in the environment. Such a system could be a complete
lighting unit comprising: one or more LEDs for converting
electrical energy into light; sockets, connectors, or receptacles
for mechanically mounting and/or electrically connecting components
to the system; optical elements for distributing light; and
mechanical components for supporting or attaching the luminaire.
Luminaires are sometimes referred to as "lighting fixtures" or as
"light fixtures." A lighting fixture that has a socket for a light
source, but no light source installed in the socket, can still be
considered a luminaire. That is, a lighting system lacking some
provision for full operability may still fit the definition of a
luminaire.
[0025] An optically transmissive cover (not illustrated) may be
attached over the lighting system 100 to provide protection from
dirt, dust, moisture, etc. Such a cover can control light via
refraction or diffusion, for example. Moreover, the cover might
comprise a refractor, a lens, an optic, or a milky plastic or glass
element. As illustrated in FIG. 2, a top cover 200 faces the
ceiling (or other surface) to which the lighting system 100 is
mounted.
[0026] The exemplary lighting system 100 is generally rectangular
in shape, and more particularly square. Other forms may be oval,
circular, diamond-shaped, or any other geometric form. Two channels
115 extend around the periphery of the lighting system 100 to form
a square perimeter. Two extrusions 110 provide the two channels
115. A row of LEDs 125 is disposed in each of the channels 115.
Each channel 115 comprises a reflective surface 105 for
manipulating light from the associated row of LEDs 125. The
reflective surface 105 can comprise a lining of the channel 115, a
film or coating of reflective or optical material applied to the
channel 115, or a surface finish of the channel 115.
[0027] In one exemplary embodiment, the channel 115 has a uniform
or homogenous composition, and the reflective surface 105 comprises
a polished surface. Thus, the reflective surface 105 can be formed
by polishing the channel 115 itself to support specular reflection
or roughening the surface for diffuse reflection.
[0028] In one or more exemplary embodiments, each channel 115 can
comprise a groove, a furrow, a trench, a slot, a trough, an
extended cavity, a longitudinal opening, or a concave structure
running lengthwise. A channel can include an open space as well as
the physical structure defining that space. In other words, the
channel 115 can comprise both a longitudinal space that is
partially open and the sidewalls of that space.
[0029] In one exemplary embodiment, the reflective surfaces 105 are
polished so as to be shiny or mirrored. In another exemplary
embodiment, the reflective surfaces 105 are roughened to provide
diffuse reflection. In another exemplary embodiment, each
reflective surface 105 comprises a metallic coating or a metallic
finish. For example, each reflective surface 105 can comprise a
film of chromium or some other metal applied to a substrate of
plastic or another material. In yet another exemplary embodiment, a
conformal coating or a vapor-deposited coating can provide
reflectivity.
[0030] Each extrusion 110 can have an aluminum composition or can
comprise aluminum. As an alternative to fabrication via an
extruding process, the channel 115 can be machined/cut into a bar
of aluminum or other suitable metal, plastic, or composite
material. Such machining can comprise milling, routing, or another
suitable forming/shaping process involving material removal. In
certain exemplary embodiments, the channels 115 can be formed via
molding, casting, or die-based material processing. In one
exemplary embodiment, the channels 115 are formed by bending strips
of metal.
[0031] Each extrusion 110 comprises fins 120 opposite the channel
115 for managing heat produced by the associated row of LEDs 125.
In an exemplary embodiment, the fins 120 and the channel 115 of
each extrusion 110 are formed in one fabrication pass. That is, the
fins 120 and the channel 115 are formed during extrusion, as the
extrusion 110 is extruded.
[0032] As illustrated, the fins 120 of each extrusion 110 run or
extend alongside, specifically behind, the associated channel 115.
As discussed in further detail below, heat transfers from the LEDs
via a heat-transfer path extending from the row of LEDs 125 to the
fins 120. The fins 120 receive the conducted heat and transfer the
conducted heat to the surrounding environment (typically air) via
convection.
[0033] The two extrusions 110 extend around the periphery of the
lighting system 100 to define a central opening 130 that supports
convection-based cooling. An enclosure 135 located in the central
opening 130 contains electrical support components, such as wiring,
drivers, power supplies, terminals, connections, etc. In one
exemplary embodiment, the enclosure 135 comprises a junction box or
"j-box" for connecting the lighting system 100 to an alternating
current power line. Alternatively, the lighting system 100 can
comprise a separate junction box (not illustrated) located above
the fixture.
[0034] Turning now to FIG. 3, this figure is a detail view of a
portion of a lighting system 100, illustrating two rows of LEDs 125
respectively disposed in two channels 115, each formed in a
respective member (specifically the extrusion 110), in accordance
with certain exemplary embodiments of the present invention. More
specifically, FIG. 3 provides a detail view of a portion of the
exemplary lighting system 100 depicted in FIGS. 1 and 2 and
discussed above. The view faces a miter joint 330 at a corner of
the lighting system 100, where two segments of extrusion 110 meet.
In an alternative embodiment, the miter joint 330 can be replaced
with another suitable joint.
[0035] In the illustrated exemplary embodiment, each row of LEDs
125 is attached to a flat area 320 of the associated extrusion 110.
The term "row," as used herein, generally refers to an arrangement
or a configuration whereby items are disposed approximately in or
along a line. Items in a row are not necessarily in perfect
alignment with one another. Accordingly, one or more elements in
the row of LEDs 125 might be slightly out of perfect alignment, for
example in connection with manufacturing tolerances or assembly
deviations. Moreover, elements might be purposely staggered.
[0036] Each row of LEDs 125 comprises multiple modules, each
comprising at least one solid state light emitter or LED,
represented at the reference number "305." Each of these modules
can be viewed as an exemplary embodiment of an LED and thus will be
referred to hereinafter as LED 305. In another exemplary
embodiment, an LED can be a single light emitting component
(without necessarily being included in a module or housing
potentially containing other items).
[0037] Each LED 305 is attached to a respective substrate 315,
which can comprise one or more sheets of ceramic, metal, laminates,
or circuit board material, for example. The attachment between LED
305 and substrate 315 can comprise a solder joint, a plug, an epoxy
or bonding line, or another suitable provision for mounting an
electrical/optical device on a surface. Support circuitry 310 is
also mounted on each substrate 315 for supplying electrical power
and control to the associated LED 305. The support circuitry 310
can comprise one or more transistors, operational amplifiers,
resistors, controllers, digital logic elements, etc. for
controlling and powering the LED.
[0038] In an exemplary embodiment, each substrate 315 adjoins,
contacts, or touches the flat area 320 of the extrusion 110 onto
which each substrate 315 is mounted. Accordingly, the thermal path
between each LED 305 and the associated fins 120 can be a
continuous path of solid or thermally conductive material. In one
exemplary embodiment, that path can be void of any air interfaces,
but may include multiple interfaces between various solid materials
having distinct thermal conductivity properties. In other words,
heat can flow from each LED 305 to the associated fins 120 freely
or without substantive interruption or interference.
[0039] The substrates 315 can attach to the flat areas 320 of the
extrusion 110 via solder, braze, welds, glue, plug-and-socket
connections, epoxy, rivets, clamps, fasteners, etc. A ridge 325
provides an alignment surface so that each substrate 315 makes
contact with the ridge 325. Moreover, contact between the
substrates 315 and the ridge 325 provides an efficient thermal path
from the LEDs 305 to the extrusion 110, and onto the fins 120, as
discussed above. Accordingly, substrate-to-extrusion contact
(physical contact and/or thermal contact) can occur at the flat
area 320, at the ridge 325, or at both the flat area 320 and the
ridge 325.
[0040] In an exemplary embodiment, the LEDs 305 comprise
semiconductor diodes emitting incoherent light when electrically
biased in a forward direction of a p-n junction. In an exemplary
embodiment, each LED 305 emits blue or ultraviolet light, and the
emitted light excites a phosphor that in turn emits red-shifted
light. The LEDs 305 and the phosphors can collectively emit blue
and red-shifted light that essentially matches blackbody radiation.
Moreover, the emitted light may approximate or emulate incandescent
light to a human observer. In one exemplary embodiment, the LEDs
305 and their associated phosphors emit substantially white light
that may seem slightly blue, green, red, yellow, orange, or some
other color or tint. Exemplary embodiments of the LEDs 305 can
comprise indium gallium nitride ("InGaN") or gallium nitride
("GaN") for emitting blue light.
[0041] In an alternative embodiment, multiple LED elements (not
illustrated) are mounted on each substrate 315 as a group. Each
such mounted LED element can produce a distinct color of light.
Meanwhile, the group of LED elements mounted on one substrate 315
can collectively produce substantially white light or light
emulating a blackbody radiator.
[0042] In one exemplary embodiment, some of the LEDs 305 can
produce red light, while others produce, blue, green, orange, or
red, for example. Thus, the row of LEDs 125 can provide a spatial
gradient of colors.
[0043] In one exemplary embodiment, optically transparent or clear
material encapsulates each LED 305, either individually or
collectively. Thus, one body of optical material can encapsulate
multiple light emitters. Such an encapsulating material can
comprise a conformal coating, a silicone gel, cured/curable
polymer, adhesive, or some other material that provides
environmental protection while transmitting light. In one exemplary
embodiment, phosphors, for converting blue light to light of
another color, are coated onto or dispersed in such encapsulating
material.
[0044] Turning now to FIG. 4, this figure depicts an internal
perspective view of a portion of a lighting system 100,
illustrating thermal management features in accordance with certain
exemplary embodiments of the present invention. More specifically,
FIG. 4 illustrates two extrusions 110 as viewed from the central
opening 130 of the exemplary lighting system 100 discussed above
with reference to FIGS. 1, 2, and 3. The two illustrated extrusions
110 have beveled faces 425 to provide the miter joint 330 shown in
FIG. 3. For clarity, FIG. 4 illustrates only one half of the miter
joint 330 (excluding two of the four extrusion segments depicted in
FIG. 3).
[0045] The fins 120 run essentially parallel to each channel 115
(within typical manufacturing tolerances that accommodate some
deviation). Moreover, the fins 120, the rows of LEDs 125, the
extrusions 110, and the channels 115 extend along a common axis
420, which has been located in an arbitrary or illustrative
position in FIG. 4.
[0046] As further illustrated in FIG. 5, each extrusion 110
comprises a slot 410 and a protrusion 405 for coupling the two,
side-by-side extrusions 110 together. The slot 410 provides a
female receptacle, and the protrusion 405 provides a male plug that
mates in the receptacle. With the protrusion 405 disposed in the
slot 410, threaded fasteners 415 hold the two extrusions 110,
thereby providing a rigid, aligned assembly. In one exemplary
embodiment, the two extrusions 110 are held together via a
tongue-in-groove connection.
[0047] Turning now to FIG. 5, this figure illustrates a cross
sectional view of two members (exemplarily embodied in the two
extrusions 110) of a lighting system 100, each providing integrated
light management and thermal management in accordance with certain
exemplary embodiments of the present invention.
[0048] FIG. 5 illustrates in further detail the fastening system
that connects the two extrusions 110 together, wherein the
protrusion 405 is seated in the slot 410. In an exemplary
embodiment, the protrusion 405 and the slot 410 are keyed one to
the other. Moreover, the slot 410 captures the protrusion 405.
Capturing the protrusion 405 can comprise encumbering (or
preventing) at least one dimension (or at least one direction) of
movement.
[0049] Inserting the protrusion 405 in the slot 410 typically
comprises sliding the protrusion 405 into the slot 410. In an
exemplary assembly procedure, two extrusions 110 are oriented
end-to-end. Next, one of the two extrusions 110 is moved laterally
until the end of the protrusion 405 is aligned with the end opening
of the slot 410. The two extrusions 110 are then moved
longitudinally towards one another so that the protrusion 405
slides into the slot 410. With the protrusion 405 so captured in
the slot 410, disassembly entails sliding the two protrusions 405
apart, rather than applying lateral separation force.
[0050] While FIG. 5 illustrates exactly two extrusions 110 joined
together, additional extrusions can be coupled to another. Each
extrusion 110 has a slot 410 on one side and a protrusion 405 on
the other side so that two, three, four, five, or more extrusions
110 can be joined to provide an array of LED lighting strips.
[0051] FIG. 5 further illustrates how a single member, in this case
each extrusion 110, can provide structural support, light
management via reflection from the surface 105, and thermal or heat
management via the fins 120. In other words, one system can provide
integrated heat and light management in a structural package.
Moreover, a unitary or single body of material, in this example
each extrusion 110, can have a reflective contour on one side and a
heat-sink contour on the opposite side. An efficient thermal path
can lead from an LED-mounting platform, associated with the
reflective contour, to the heat-sink contour. As discussed above,
such a LED-mounting platform, a reflective contour, and a heat-sink
contour can be exemplarily embodied in the flat area 320, the
reflective surface 105, and the fins 120, respectively.
[0052] Although FIG. 5 illustrates the reflective contour as a
parabolic form, the reflective surface 105 can be flat, elliptical,
circular, convex, concave, or some other geometry as may be
beneficial for light manipulation in various circumstances.
Similarly, the fins 120 can have a wide variety of forms, shapes,
or cross sections, for example pointed, rounded, double convex,
double concave, etc. Moreover, although eight fins 120 are
illustrated for each extrusion 110, other embodiments may have
fewer or more fins 120. As discussed above, the fins 120 transfer
heat, produced by the LEDs 305, to surrounding air via circulating
or flowing air. Thus, the fins 120 promote convection-based
cooling.
[0053] Turning now to FIG. 6, this figure illustrates a plot of
simulated thermal contours of a portion of a lighting system 100
providing integrated light management and thermal management in
accordance with certain exemplary embodiments of the present
invention. More specifically, FIG. 6 illustrates temperature
gradients via showing lines (or regions) of equal (or similar)
temperature for a cross section of the exemplary lighting system
100 illustrated in FIGS. 1-5 and discussed above.
[0054] The illustrated cross section cuts though a lower cover 600
(not depicted in FIGS. 1-5) and the extrusions 110. The illustrated
temperature profile, which was generated via a computer simulation,
demonstrates how the fins 120 transfer heat to air 610.
Accordingly, heat moves away from the LEDs 305 and is dissipated
into the operating environment, thereby avoiding excessive heat
buildup that can negatively impact operating efficiency and can
contribute to premature failure.
[0055] Turning now to FIG. 7, this figure illustrates a plot of
simulated thermal contours of a lighting system 100 comprising LEDs
305 and a capability for managing heat and light output by the LEDs
305 in accordance with certain exemplary embodiments of the present
invention. Similar to FIG. 6, FIG. 7 illustrates temperature
gradient via showing lines (or regions) of equal (or similar)
temperature for an exemplary embodiment of a lighting system
100.
[0056] The thermal management provisions of the lighting system 100
transfer heat away from the LEDs 305 to support efficient
conversion of electricity into light and further to provide long
LED life.
[0057] Turning now to FIG. 8, this figure illustrates a flowchart
of a method 800 of operation of a lighting system 100 comprising
LEDs 305 and a capability for managing heat and light output by the
LEDs 305 in accordance with certain exemplary embodiments of the
present invention.
[0058] At step 805 of the method 800, the LEDs 305 receive
electricity from a power supply that may be located in the
enclosure 135 or mounted on the substrate 315, for example. In one
exemplary embodiment, an LED power supply delivers electrical
current to the LEDs 305 via circuit traces printed on the substrate
315. The current can be pulsed or continuous and can be pulse width
modulated to support user-controlled dimming. In response to the
applied current, the LEDs 305 produce heat while emitting or
producing substantially white light or some color of light that a
person can perceive. As discussed above, in one exemplary
embodiment, at least one of the LEDs 305 produces blue or
ultraviolet light that triggers photonic emissions from a phosphor.
Those emissions can comprise green, yellow, orange, and/or red
light, for example. In other words, the LEDs 305 produce light and
heat as a byproduct.
[0059] At step 810, the reflective surfaces 105 of the channels 115
direct the light outward from the lighting system 100. The light
emanates outward and, to a lesser degree, downward. Directing the
light radially outward, while maintaining a downward aspect to the
illumination pattern, helps the lighting system 100 illuminate a
relatively large area, as may be useful for a parking garage or
similar environment.
[0060] At step 815, the heat generated by the LEDs 305 transfers to
the fins 120 via conduction. As discussed above, in an exemplary
embodiment, the materials in the heat transfer path between the
LEDs 305 and the fins 120 can have a high level of thermal
conductivity, for example similar to or higher than any elemental
metal. Accordingly, in an exemplary embodiment, the heat conduction
can be efficient or unimpeded.
[0061] At step 820, the fins 120 transfer the heat to the air 610
via convection. In an exemplary embodiment, the heat raises the
temperature of the air 610 causing the air 610 to circulate, flow,
or otherwise move. The moving air carries additional heat away from
the fins 120, thereby maintaining the LEDs 305 at an acceptable
operating temperature. As discussed above, such a temperature can
help extend LED life while promoting electrical efficiency.
[0062] Technology for managing heat and light of an LED-based
lighting system has been described. From the description, it will
be appreciated that an embodiment of the present invention
overcomes limitations of the prior art. Those having ordinary skill
in the art will appreciate that the present invention is not
limited to any specifically discussed application or implementation
and that the embodiments described herein are illustrative and not
restrictive. From the description of the exemplary embodiments,
equivalents of the elements shown herein will suggest themselves to
those having ordinary in the art, and ways of constructing other
embodiments of the present invention will appear to practitioners
of the art. Therefore, the scope of the present invention is to be
limited only by the claims that follow.
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